All human movements happen in the face of uncertainty. The objective of this thesis was to determine how the nervous system deals with sensorimotor uncertainty when adapting to visuomotor perturbations during walking. We asked subjects to walk and step on a target while wearing prism goggles that shifted the perception of the target’s location. We manipulated uncertainty by varying the strength and perturbation direction of the prism lenses on a trial-by-trial basis in three conditions: no, low and high noise. We measured lateral end-point errors of foot placement from the target in a visuomotor adaptation paradigm with baseline, adaptation and post-adaptation phases. Results showed increases in error variability, slower adaptation rates, and smaller errors in the first adaptation trial when increasing uncertainty. These results suggest that the nervous system relies on a predictive mechanism, which is sensitive to errors, and weights prior experiences to adapt walking.
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Thesis advisor: Marigold, Daniel S.
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